DK175892B1 - Windmill control method involves providing control signal for adjusting common basic adjustment angle of blade, based on measured windmill load and wind speed obtained based on deflection of blade along rotational axis of rotor - Google Patents

Abstract

The load on a windmill is determined, and wind speed is measured based on deflection of the blades (4) along rotational axis of a rotor (1a). A control signal is provided for adjusting common basic adjustment angle of the blades, based on the measured load and wind speed, for controlling the rotational speed of the rotor. An independent claim is also included for windmill.

Description

in DK 175892 B1

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a method for controlling a wind turbine, especially in island operation, which comprises a rotor having a substantially horizontal axis of rotation, at least two vanes each connected at one end 5 to the rotor and extending therefrom. substantially along a blade axis about which the blade can be rotated to an adjustment angle of the blade, a blade adjusting device for adjusting a common basic adjustment angle of the blades, means for detecting the magnitude of the initial adjustment angle, means for detecting the wind turbine load, means for detecting the blade deflection in the direction of rotation, by which method the rotational speed of the mill rotor is controlled by adjusting the basic setting angle, providing a control signal for the wing adjusting device depending on the load and the wind speed.

The invention further relates to a wind turbine comprising a rotor with substantially horizontal axis of rotation, at least two blades each connected at one end to the rotor and extending therefrom substantially along a blade axis about which the blade can be rotated. through a first bearing for a blade setting angle, a blade adjusting device for adjusting a common basic setting angle for the blades, a hinge between the blade and the rotor with a hinge axis extending in a direction transverse to the blade axis and the direction of rotation of the rotor, each of the blades in particular, it can be deflected in the direction of the rotor axis of rotation by rotating the respective hinge axis. A mill of this kind is known from the applicant's own DK-B-174 346.

An example of a method of the above

I DK 175892 B1 I

i 2 I

In kind, for controlling a wind turbine can be found in GB-A-2 023 H

I 237. According to this writing, the wind speed at H

With the help of a wind meter, which is located on the wind turbine H

In a gondola or a place where it is not affected by wind

In the rotation of the turbine. H

In US-A-6,619,918 discloses a mill which, among other things, I

In the second on the wings is provided with strain-gauges with

In order to monitor the deflection of the wings in order to

In avoiding collision with the mill tower. With an intention- I

In placing the strain gauges, such a mill I will

You could be used to practice the method of I

In the invention. IN

Other examples of the prior art can be found in: H

In US-A-6,361,275, which relates to the reduction of

I 15) loads on a mill's components. In addition, H is measured

In voltages on various components, eg the wings, H

I using strain gauges; a desired angular position H

I for each wing independently of the other wings H

They are determined and an adjusting device sets the re- I

20 spectral wings in the desired positions to avoid

peak load and extend the life of the mill. There- I

also turn wind tabs or indicators mounted on I

In the wings to measure the wind inflow angle. IN

US-A-4,183,715 discloses a mill with wings, I

I 25 turning up to the wind due to aerodynamic I

In the lift. A solder or servo motor counteracts rotation I

In to control the mill. In the embodiment with servo- I

In tor, the wind speed can be measured with a wind meter on the mill

In the dormitory is involved in the management. IN

In US-A-4 297 076, a mill with strain gauge discloses for monitoring the load of the blades.

In the signals from these strain gauges, H is used

In determining whether the turbine points up in the wind and, if so, H

3 DK 175892 B1 provide a signal to a bend motor. In addition, the strain gauge signals are used to adjust the angles of the blade tip of the mill to avoid sustained overload and oscillation load of the mill hub. The wind turbine's control system includes a closed loop based on the speed and an open loop based on the power taken from the mill by the grid to which it is connected and the wind speed measured with a wind meter. It is not clear from the script exactly in which direction the strain on the wings is measured by the strain gauges. However, the strain gauges appear to be located in the middle of the profiled portion a distance from the wing base so that the strain gauges will measure in a direction perpendicular to the blade profile, which is inclined to a plane perpendicular to the axis of rotation of the rotor. Thereby, the strain gauges will measure in directions not parallel to the direction of rotation of the rotor.

DD-A-252 640 discloses a turbine which aims to utilize, by means of a system for controlling the setting angle of the blades, to optimally utilize the wind power, maintain a certain speed and avoid overload. Therefore, a bending moment acting on the blade root is measured and a signal proportional to the bending torque is processed in dependence of a signal from a rpm control device to a control pulse to a wing setting motor. The measurement of the mill's power is not mentioned and the bending moment seems to be measured in a direction approx. 45 ° from the rotor axis of rotation.

In island operation of a mill, ie. operation of a mill that is not connected to a grid with a frequency that can be used to control the mill, it is difficult to control

DK 175892 B1 I

precisely control the speed of the mill, thus I

that through an alternator a 1 may be obtained

alternating current with a substantially constant frequency

frequency. This problem is mentioned, inter alia, in the above-mentioned

5 th GB-A-2 023 237, which discloses a method for I

control of a wind turbine. IN

A prerequisite for precise control of an I

however, the wind turbine is an accurate and reliable measurement

of the wind load on the mill, as it is this

10 loading, which is converted by the milling blades to rotate I

onsenergy, which can further be converted into electrical I

energy in a generator.

The object of the invention is in one aspect that

provide a method for controlling a wind turbine, I

15 whereby the speed of rotation of the mill and thus fre- I

the number of alternating current generated by a connected I

generator, can be kept constant within narrow tolerances.

ting. IN

The purpose is, in another aspect, to provide an I

20 wind turbines which can be used to carry forward

method.

The purpose is fulfilled under the first aspect of I

a method of the kind mentioned initially, I

which is peculiar in that as a measure of wind speed I

25, the blade deflection is used in the rotor rotation

axis of direction. IN

The purpose is fulfilled under the second aspect of a - I

wind turbine of the aforementioned kind, which is peculiar to, I

comprising a device for detecting the magnitude I

30 of a blade deflection in the rotor axis of rotation

see direction and means for detecting basic I

the size of the position angle and the means of transfer

ring of a detected wing deflection size and an I

5 DK 175892 B1 detected the default setting angle size for a control device.

The invention is based on the recognition that because wind is an unstable size with turbulence and wind shocks such that the wind load can vary considerably within a few meters distance, the wind turbine's wings must be used as a wind meter if an accurate measure of the wind load is to be achieved. mill. Accordingly, according to the invention, the blades of the turbine are used as wind meters to provide input signal to the turbine controller.

An accurate measure of the wind load, and in particular its changes, is necessary to be able to control a mill with a fast response, which is a necessity for precise control.

In preferred embodiments of the method according to the invention, the rotor speed of rotation is measured and the measured value is used in the provision of the control signal for the wing adjusting device.

In a practical embodiment, the deflection of the blade with the largest deflection is used as a measure of the wind speed.

By using the rotor speed of rotation in the control, a closed loop can be established to ensure that the speed of rotation does not drift relative to the desired value.

If only the speed of control is used for control, a control response is established only when the speed of rotation has changed.

30 By using the current wind load on the wind turbine blades, a control response can be established as the wind load changes before this change has resulted in a changed speed of rotation.

I DK 175892 B1 I

In a practical embodiment of the wind turbine I

According to the invention there is a device for detecting

ring of the deflection of the wing with the largest deflection

equipment. Furthermore, means for detecting are preferably present

5 increasing the rotor speed and means of - I

transferring the detected size to a control I

unit. IN

A control unit for providing a control signal

nal to the wing adjusting device may be part I

10 of the mill. Alternatively, an external controller may be I

connected to the mill. In practice, the control unit will re- I

grab a computer. IN

The method of control according to the invention I

is intended primarily for the control of a wind turbine I

15 in island operation, where the output of the mill must be weak

to the demand, as there will be no other

sources to regulate. However, the process can also be turned on

can be used on a wind turbine in a grid where progress I

the method can be used to provide one in the tissue

20 late constant output from the wind turbine, so I

that the management of the network as a whole is facilitated. IN

The invention will be explained in the following

more particularly by way of example examples

view of the schematic drawing on which I

Fig. 1 shows a section along the main axis of an I

wind turbine rotor housing as indicated by I-I in FIG. 2, I

FIG. 2 is a sectional view as indicated by II-II in FIG. IN

1 and I

FIG. 3 is a section along the main axis through guided I

30 len. IN

Referring to FIG. 1 and 2 have a wind I

mill according to the invention a main shaft 1 extending I

turns along and can rotate about a major axis la. Main axis I

7 DK 175892 B1 1 extends into the gondola of the mill not shown to a gear for transferring rotational energy to an alternator in a manner known per se.

The main shaft 1 is pivotally connected to and carries a rotor housing 2 which carries two bearing housings 3, each carrying a vane 4. The rotor housing 2 and its arrangement and equipment are symmetrical about the main shaft 1a. Therefore, in the following, only a blade 4 and its attachment to the rotor housing 2 will be described.

The mill described herein with reference to the drawing has two blades, but those skilled in the art will appreciate that the invention can be applied to mills having multiple, for example, three blades. Furthermore, the mill described with reference to the drawing is a so-called runner, ie.

15 that the rotor with its wings is on the reading side of the mill tower not shown. Those skilled in the art will appreciate that the invention may also be applied to a front runner, i.e. a mill whose rotor and wings are on the windward side of the mill tower.

The bearing housing 3 is hinged to the rotor housing 2 by means of two bearings 5 so that the bearing housing 3 can pivot about an axis 3a extending in a plane perpendicular to the main axis 1a.

In the bearing housing 3, through two bearings 6 is mounted a 25 wing rod 7, which is thereby rotatable about a wing axis 7a. The blade root 7 carries at its one end the wing 4 and is at its other end pivotally connected to a tapered sprocket 8, which is engaged by another tapered sprocket 9. The second tapered sprocket 9 is fixed 30 to an adjustment shaft 10 which supports a worm wheel 11. The adjusting shaft 10 with the sprocket 9 and worm wheel 11 is mounted rotatably through bearings 12 about the axis 3a of the bearing housing 3.

DK 175892 B1 I

The worm wheel 11 engages a worm 13,

which can be rotated by means of a hollow guide shaft 14 which I

extends coaxially through the main shaft 1. I

Through the hollow guide shaft 14 extends 1

5 is a push rod 15 which, in its position shown in FIG. 1 end bearing - I

a contact plate 16. A rocker arm 17 can tilt about a bearing

at 18 and is at one end connected to the bearing housing I

3 through a bracket 19 on the bearing housing 3 and a joint 20 such as I

through hinges 21 are connected to bracket 19 and I

10 the rocker arm 17. At its end opposite the joint 20, you carry

the rocker arm a pressure roller 22 which may abut against one another

calf plate 16. I

In operation, the centrifugal force will seek to

position the wing 4 with the wing axis 4a perpendicular to the main I

15, while the pressure from the wind indicated by 1

an arrow 23 in FIG. 1, will seek to push the wing backward

about the axis 3a to a deflection angle a

In the case of gravity, the force of gravity will rotate one wing down about the axis 3a. Therefore, the rotor housing 2 preferably carries

20 not showing stabilizing springs which seek to hold

the wings 4 perpendicular to the main axis 1a. Such a state I

bilayer spring may be attached to a bracket 24 I

at ivert rental house 3. I

It is understood that by pivoting the wing 4 about the axis I

25a 3a, the tapered sprocket 8 of the wing root 7 will roll on I

the tapered sprocket 9 of the shaft 10, whereby I

the wing 7 will rotate correspondingly on the wing axis 7a. This rotation does not affect the second, not shown wine,

ge. IN

30 It is further understood that rotation of the worm 13 I

by means of the control shaft 14 will result in a rotation

adjusting the adjusting shaft 10 and thus turning I

of the wing 4. This rotation applies to both wings, I

9 DK 175892 B1 both the one shown and the one not shown.

In FIG. 3 is shown the mill part. Thus, FIG. 3 is a view similar to that of FIG. 1 shows the opposite end of the main shaft 1, the steering shaft 14 and the push rod 15.

The main shaft 1 pivotally carries a first cylindrical sprocket 26, and the steering shaft 14 pivotally pivots a second cylindrical sprocket 27. The first cylindrical sprocket 26 is engaged by a third cylindrical sprocket 28 and the second cylindrical sprocket 27 is engaged by a sprocket 29. a fourth cylindrical gear 30. The third and fourth cylindrical gears 28 and 30 are respectively pivotally supported by shafts 31 which are fixedly mounted in the 15 gondola of the wind turbine not shown, and which are firmly connected to each of two first, opposite, tapered gears 32 in a differential with a differential housing rotatable via bearings 38 33. Rotating about a differential shaft 34 are two other opposed tapered gears 20 35 which engage the first opposed tapered gears 32. The differential housing 33 carries on its circumferential surface is a worm wheel 36 which engages a worm 37 fixedly mounted in the gondola rotatable about an axis perpendicular to the drawing p. loan.

25 The first and third cylindrical gears 26 and 28 have the same diameter, and the second and fourth cylindrical gears 27 and 30 have the same diameter.

As a result, the differential shaft 34 will stand still when the main shaft 1 and the steering shaft 14 have the same rotation speed and direction. If the main shaft 1 and the steering shaft 15 do not have the same rotational speed and direction, the differential shaft 34 will rotate about a differential coaxial axis carrying the shafts 31.

I DK 175892 B1 I

I 10 I

the housing 33 and the worm wheel 36. The latter will by its I

In operation the worm 37. I

I If the main shaft 1 and the steering shaft 14 rotate

At different speeds it will cause a rotation

In 5 of the worm 13 in the rotor housing 2 and thus a turn of ^ I

In the wings. Therefore, through the worm 37, a basic

At the angle of adjustment of the wings. IN

A revolution counter 40 is via a fifth cylinder

In Drisk gear 41, which engages with the first

In 10 cylindrical gears 26, connected to the main shaft and I

You thus indicate its rotational speed. IN

A position meter 42 has a key 42a in system I

Towards the end of the push rod 15 and therefore provides via tilting

In the parchment 17 a measure of the deflection angle α of the wing I

In 15 with the greatest deflection angle. IN

A steering motor 43 carries pivotally fixed to its shaft I

In 44, a sixth cylindrical gear 45 which engages I

with the second cylindrical sprocket 27. thereby controlling

In the steering motor 43 the steering shaft 14's rotation. IN

The control motor 43 is controlled by one with a microprocessor

Cessor-provided controller 46 which receives itself

In worms 37, turn counter 40, position I

In the odometer 42 and also a signal indicating the condition

In the loading on the mill, for example, an indication of the I

In 25 power output of the generator not shown. IN

Thus, the control device 46 receives in a foil

retracted embodiment the following signals:

I A: measure of the blade 's initial angle of adjustment

In deduction from worm 37, I

In 30 B: measure of the rotation of the mill (main shaft 1)

Speed of speed deduced from the tachometer 40, I

I C: measure of wind speed against the mill blades I

I or wind load on the milling blades, expressed by I

11 DK 175892 B1 the bending angle α deduced from the position sensor 42, and D: measure of the mill's power as delivered by the generator.

In the embodiment described here, the moth 5 is operated in island operation, i.e., it is not connected to a larger net. As far as possible, the rotational speed of the turbine must be kept constant because the frequency of the power supplied by the generator is proportional to the rotational speed of the turbine and this frequency is desired as constant as possible.

During operation, the power of the mill must be varied as required, since excess power from the mill will be absorbed as kinetic energy in the mill rotating parts, ie. that the speed of the mill will increase, which is undesirable as mentioned.

At constant wind loads, the effect can be set by adjusting the blade's default setting angle.

At constant power demand, the power produced by the wind can be adjusted by adjusting the blade's default setting angle.

Because both the wind load and the power demand in reality vary randomly, the control motor 43 is controlled by the control device 46 in an open loop control at 25, the control device determining a desired basic setting angle on the basis of the measurements C and D for the wind load and the reduced power respectively.

As a starting point, the steering shaft 14 is rotated at the same rotational speed as the main shaft 1. In the event of a change in the basic setting angle of the blades, the steering shaft 14's rotational speed is increased or decreased. The changed default setting angle is deduced as the target A from the worm 37. When the target A corresponds to _ _____ __ '

I DK 175892 B1 I

the control set 4 by the control device 4 6 is adjusted

the speed of the shaft 14 to that of the main shaft 1

sheath speed of rotation. IN

To prevent the rotational speed of I

5 the main shaft 1 drives, the open-loop mounting guide is superimposed - I

of a closed-loop party control with feedback of I-I

easy D from the tachometer to the control device I

Experiments have shown that in this way I can be obtained

10 shows an alternating current from the generator at a frequency which I

only +/- 2.5% deviates from what you want. IN

In addition to the basic setting, the individual blades will

the angle change their current setting angle as I

due to their current deflection angle α on the same I

15, as described in the applicant's above-mentioned older patent

patent No. 174,346

Claims (7)

A method of controlling a wind turbine, preferably in island operation, said wind turbine comprising a rotor with substantially horizontal axis of rotation, at least two vanes each connected at one end to the rotor and extending therefrom therein. substantially along a blade axis about which the blade can be rotated to an adjustment angle of the blade, a blade adjustment device for adjusting a common basic adjustment angle of the blades, means for detecting the magnitude of the angle of adjustment, means for detecting the wind turbine deflection means in the rotation axis, by which method the rotor speed of the turbine is controlled by adjusting the basic setting angle, providing a control signal for the blade adjusting device depending on the load and the wind speed, characterized in that the blade deflection of the blade speed is used as a measure of the wind speed. omdrejningsa change direction. Method according to claim 1, characterized in that the rotational speed of the rotor 25 is measured and used in the provision of the control signal for the wing adjusting device. Method according to claim 1 or 2, characterized in that the deflection of the blade with the largest deflection is used as a measure of the wind speed. A wind turbine comprising a rotor with substantially horizontal axis of rotation, i. _____._____— d DK 175892 B1 at least two vanes, each of which is connected at one end to the rotor and extends therefrom substantially along a blade axis about which the vane can be rotated through a first bearing to an adjustment angle of the blade, in a blade adjusting device for adjusting a common basic adjustment angle of the blades, in a hinge between the blade and the rotor, with a hinge axis extending in a transverse direction of the blade axis and the direction of rotation of the rotor, whereby the blades each can be deflected in the direction of the rotor axis of rotation by rotation of the respective II hinge axis, characterized in that II comprises a device for detecting the magnitude of the deflection of an IH blade in the direction of rotation of the rotor axis and means for detecting the basic adjustment angle II size of the lens as well as means for transmitting a detected II deflection size and a detected I In 20 basic setting angle size for a control device. IN Wind turbine according to claim 4, characterized in that it comprises a device for detecting the deflection of the blade with the largest deflection. IN Wind turbine according to claim 4 or 5, characterized by means for detecting the rotational speed of the rotor I and means for transmitting the detected size to a control unit. IN Wind turbine according to claims 4-6, characterized in that it comprises a control unit for providing a control signal for the wing adjustment device. IN